Touch Detection of UIButton added as SubView in UIScrollView

Question

I have a scroll view with many buttons. I want to detect the touches on UIButton inside scrollView but not been able to get them. I tried by subclassing uiscrollview, and uibutton but failed. I want to detect touches on button if user holds that button for a short time, say 2 sec. And then i want to drag the button to place where user can drag it on scroll view. Plz help me.

Answer 1

You don't need to subclass.

Try to attach to your UIButton a UILongPressGestureRecognizer .

Have a look here for more info.

Gesture recognizers are available from iOS 3.2 and make very easy all things related to gestures. Here you can find a tutorial.

If you want to support previous versions, you have to resort to a different method:

1. add UIControlEventTouchUpInside and UIControlEventTouchDown actions to your button;

2. in the touchDown handler start counting time (set a variable with current time);

3. in touchUp handler stop counting time; measure the difference and if is above your threshold, fire you action.

If this does not work, provide some more information as to why it doesn't, please.

Answer 2

You can set a tag for each button on the scrollView , then like @sergio said add a UILongPressGestureRecognizer (or a uicontrolevent) to each button, so when you are setting the pages in the scrollview you could add:

[button addTarget:self action:@selector(someAction:)  forControlEvents:UIControlEventTouchUpInside];

or

UILongPressGestureRecognizer *twoSecPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(someAction:)];
            [twoSecPress setMinimumPressDuration:2];
            [button addGestureRecognizer:twoSecPress];
            [twoSecPress release];

and in your action..

    -(IBAction)someAction:(id)sender{
      UIButton *button=(UIButton*)sender;
          if(button.tag==YOUR_TAG){
            //do something
    }
}

or

-(void)someAction:(UILongPressGestureRecognizer *)recognizer {
    if (recognizer.state == UIGestureRecognizerStateBegan) {
            if ([recognizer.view isKindOfClass:[UIButton class]]) {
                UIButton *tmpButt=(UIButton *)recognizer.view;
                NSLog(@"%d", tmpButt.tag);
    }
}

(obviously add UIGestureRecognizerDelegate on your.h)